Abstract: Cell behavior is affected by nanostructured surface, but it remains unknown how ionizing radiation affects cells on nanostructured surface. This paper reports an experimental investigation of X-ray radiation induced damage of cells placed on an array of vertically aligned silicon nanowires. X-ray photoelectrons and secondary electrons produced from nanowire array are measured and compared to those from flat silicon substrate. The cell functions including morphology, viability, adhesion and proliferation have been examined and found to be drastically affected when cells are exposed to X-ray radiation, compared to those sitting on flat substrate and those only exposed to X-ray. The enhanced cell damage on nanowires upon X-ray exposure is attributed to nanowire enhanced production of photoelectrons including Auger electrons and secondary electrons, which have high escaping probability from sharp tips of nanowires. The escaped photoelectrons ionize water molecules and generate hydroxyl free radicals that can damage DNAs of cells. An inference of this work is that the contrast in scanning electron microscopy is useful in assessing the effects of nanomaterials for enhanced X-ray radiation therapy.

Key words: Edge enhancement, Silicon nanowire array, X-ray radiation, Photoelectron, Cell damage